The usual way to treat air laden with grease and odors which is produced by a cooking appliance is to extract air from above the appliance to the outside by means of an extraction unit. The extraction unit is mounted above the appliance. This extraction unit is generally in the form of a hood and includes a number of filters and/or particle traps to trap grease and other particles in the air. Some sort of deodorizing means is also often included such as an activated carbon filter or a source of fragrant masking oil.
The problems with mechanical filters are that they tend to need regular replacement or cleaning and also that when laden with grease etc., they represent a significant fire hazard.
Proposals have been made to use ultra-violet light to decontaminate air in air extraction units of the type described above. In these arrangements ultra-violet tubes are provided above the air inlet behind the front wall of the unit. This front wall therefore hides the tubes from direct view. However since these units are fabricated from stainless steel, when the tubes are in operation light from them escapes through the air inlet and is reflected off the downwardly extending rear wall of the unit, thus making the light clearly visible.
The inventors have realized however that even reflected light from the UV tubes typically used in these applications is hazardous despite the previous tacit assumption to the contrary.